The Centre d'Etude du Polymorphisme Humain (CEPH) proposes to enhance the use of the primary linkage map of the human genome, nearing completion, in localizing genes which determine genetic diseases. This will be done by developing a collection (kit) of 200 probes for primary RFLP markers, those located at 20 centimorgan intervals on all chromosomes, and then distributing the entire collection (genome kit) or subsets (chromosome kits), upon request, to qualified members of the scientific community. Kits will be made available at no cost to these users. Kits will be distributed on the basis that they will not be used for any commercial purposes. The users will participate in a collaboration in which they contribute to and share a data base, provided by CEPH, for genotypic data generated with kit probes used on DNA from disease families. Probes to be included in kits will be those for primary markers of linkage maps of each chromosome constructed from genotypic data generated from the CEPH reference panel of 40 families. The probes will be requested from appropriate investigators with the understanding that they will be distributed to any competent researcher requesting a kit, that all findings resulting from use of the probes will be in the public domain and that each probe will be contributed to the NIH Repository of Human Probes and Libraries at the American Type Culture Collection (ATCC). Probes for kits will be produced in large batches at ATCC and sent to CEPH for quality control testing and distribution. The CEPH will help kit users analyse their linkage data by providing computer programs, consultation and, for selected diseases, data analysis. Kits will be updated annually with probes of markers more informative than original primary markers. Supplementary kits containing probes for markers on higher resolution chromosome maps will also be available.